GPT-5.1 vs Claude 4 Sonnet
Head-to-head specifications
| Metric | GPT-5.1 | Claude 4 Sonnet | Difference |
|---|---|---|---|
| Intelligence Index | 37.0 | 29.0 | +27.6% |
| Coding Index | 49.4 | 37.6 | +31.4% |
| Agentic Index | 21.0 | 16.6 | — |
| Context window | 512K tokens | 1M tokens | — |
| Blended price ($/1M tokens) | $0.77 | $1.20 | -35.8% |
| Access | Proprietary API | Proprietary API | — |
- GPT-5.1 leads overall capability (Intelligence Index 37.0 vs 29.0).
- GPT-5.1 is the cheaper model to run at $0.77/1M blended tokens — about 1.6× cheaper.
- Claude 4 Sonnet offers the larger context window (1M tokens), useful for long documents and codebases.
Verdict: GPT-5.1 or Claude 4 Sonnet?
GPT-5.1 advantages
- General intelligence (+22%)
- Coding ability (+24%)
- Agentic task performance (+21%)
- Affordability (+36%)
Claude 4 Sonnet advantages
- Context window (+49%)
Which should you choose?
- Choose the GPT-5.1 if you need the strongest overall reasoning and accuracy.
- Choose the Claude 4 Sonnet if you work with long documents or large codebases.
- Choose the GPT-5.1 if coding and software development are your main workload.
Value for money
GPT-5.1 offers more intelligence per dollar (2.0× the Intelligence-Index-per-cost of the alternative), making it the stronger value for high-volume use.
GPT-5.1 vs Claude 4 Sonnet: which should you choose?
GPT-5.1 — OpenAI multimodal model with an Intelligence Index of 37, a 512K-token context window and a blended price of $0.77/1M tokens.
Claude 4 Sonnet — Anthropic multimodal model with an Intelligence Index of 29, a 1M-token context window and a blended price of $1.2/1M tokens.
GPT-5.1 vs Claude 4 Sonnet: GPT-5.1 scores higher on the Intelligence Index. GPT-5.1 leads overall capability (Intelligence Index 37.0 vs 29.0). GPT-5.1 is the cheaper model to run at $0.77/1M blended tokens — about 1.6× cheaper.
Capability: intelligence, coding and agentic work
On the composite Intelligence Index the GPT-5.1 scores 37.0 versus 29.0. For software development, the Coding Index puts GPT-5.1 ahead (49.4 vs 37.6). On agentic, multi-step tool-use tasks, GPT-5.1 measures stronger. Composite indices summarize many evaluations, but always test on your own workload before committing.
Context window and speed
The Claude 4 Sonnet accepts up to 1 million tokens per request, which sets how much documentation, transcript or code it can reason over at once.
Pricing and access
At blended per-token rates, GPT-5.1 is the cheaper model to run ($0.77 vs $1.20 per 1M tokens). GPT-5.1 is proprietary api and Claude 4 Sonnet is proprietary api. Open-weight models can be self-hosted, trading per-call cost for infrastructure you manage; for production also weigh rate limits, throughput and data-residency requirements.
The verdict
Both are credible choices in the ai model comparison space; the specification table above lays out every metric so you can weigh the trade-offs that matter to you. Pick the one whose strengths line up with how you will actually use it.
Frequently asked questions
Is the GPT-5.1 better than the Claude 4 Sonnet?
GPT-5.1 is the clearly stronger overall choice, winning most of the dimensions that matter. GPT-5.1 leads overall capability (Intelligence Index 37.0 vs 29.0).
What is the main difference between the GPT-5.1 and the Claude 4 Sonnet?
GPT-5.1 leads overall capability (Intelligence Index 37.0 vs 29.0). GPT-5.1 is the cheaper model to run at $0.77/1M blended tokens — about 1.6× cheaper.
Which is better value?
GPT-5.1 offers more intelligence per dollar (2.0× the Intelligence-Index-per-cost of the alternative), making it the stronger value for high-volume use.
Which should I choose?
Choose the GPT-5.1 if you need the strongest overall reasoning and accuracy. Choose the Claude 4 Sonnet if you work with long documents or large codebases.
Methodology
Large language models are compared on independent leaderboard metrics: an Intelligence Index (a composite of reasoning and knowledge evaluations), Coding and Agentic indices where measured, community arena Elo, maximum context window, a blended API price per million tokens (weighted across cache-hit, input and output rates), and measured output speed in tokens per second. Where a model ships multiple reasoning-effort variants, we report its strongest variant. Benchmarks capture only part of real-world quality, which also depends on tool use, latency, safety and task fit — and this space moves quickly, so figures reflect the leaderboard snapshot on the page date.